Bundled with Garmin's HRM-Tri heart rate monitor, the Fenix 5 Performer Bundle offers a wealth of insightful metrics for multi-sport athletes rigorously training for an upcoming race. The bundled HRM-Tri measures what Garmin refers to as Extensive Running Dynamics, such as cadence, stride length, ground contact time, ground contact time balance, vertical oscillation, and vertical ratio, alongside traditional heart rate monitoring. For swimming, it wirelessly feeds heart rate data after you're finished to the Fenix 5, which is a huge plus for assessing your swim performance for an upcoming race. Please note, Garmin recommends this heart rate monitor mainly for open water environments, as pushing off the walls of indoor pools may cause slippage issues with the strap. Offering a long-awaited refresh to the popular Fenix 3, the Fenix 5 retains the popular sport-monitoring capabilities, but in a sleeker 47-millimeter case with easier swapping of wrist bands. Instead of messing with tools, the Fenix 5 now swaps QuickFit bands with a simple click. Another notable upgrade, the battery lasts up to 24 hours in GPS mode and 60 hours in UltraTrac mode. Resolution is slightly better than the previous version, making it easier to view your exercise data in bright outdoor environments. Besides the subtle upgrades, the Fenix 5 retains many of the same features of the Fenix 3, which is a good thing if you're seeking one of the most comprehensive sport and navigation watches on the market. Like previous models, smartphone updates keep you on track with your daily schedule, incoming emails, and urgent texts. Another popular feature carried over, wrist-based heart rate monitoring is built into the watch, so you can leave the HRM-Tri heart rate monitor behind on casual neighborhood runs and hikes in the hills. Advanced Performance Metrics give you aerobic and anaerobic benefits from grueling workouts, so you can see how it's paying off in the long run and compare yourself to peers...